Thermal instability of thin accretion disks in the presence of wind and toroidal magnetic field

TL;DR

This paper analyzes how magnetic fields and winds influence the thermal stability of thin accretion disks, revealing that magnetic fields generally stabilize disks, while winds can either stabilize or destabilize depending on their nature.

Contribution

It provides a comprehensive stability analysis considering both magnetic fields and winds, highlighting the wind's dual role in disk stability, which was not fully explored before.

Findings

Magnetic fields have a stabilizing effect on accretion disks.

Winds can either stabilize or destabilize disks depending on their type.

Winds can explain thermal stability in models where magnetic pressure alone is insufficient.

Abstract

We study the local thermal stability of thin accretion disks. We present a full stability analysis in the presence of a magnetic field and more importantly wind. For wind, we use a general model suitable for adequately describing several kinds of winds. First, we explicitly show that the magnetic field, irrespective of the type of wind, has a stabilizing effect. This is also true when there is no wind. In this case, we confirm the other works already presented in the literature. However, our main objective is to investigate the local thermal stability of the disk in the presence of the wind. In this case, interestingly, the response of disk is directly related to the type of wind. In other words, in some cases, the wind can stabilize the disk. On the other hand, in some cases, it can destabilize the disk. We found that in some thin disk models where the magnetic pressure cannot explain the stability of the disk by including a typical contribution for magnetic pressure, the wind can provide a viable explanation for the thermal stability.